#include<iostream.h>
#include<stdio.h>
int main ()
{long int P,Q,N,contor=1,truth=1,truth2=3;
freopen ("fractii.in", "rt" ,stdin);
freopen ("fractii.out","wt" ,stdout);
cin>>N;
if (N==1) cout<<truth;
else if (N==2) cout<<truth2;
else {for (contor=2*N-1,P=2;P<=N;P++)
          {Q=2;
	   while (Q<=N) {if (P%Q!=0) contor++;
	                 else if (Q%P!=0) contor++;
			Q++;}}
cout<<contor;}
return 0;}